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Sept. 8, 2011 -- About one in four adults age 35 and over can be expected to develop chronic obstructive pulmonary disease (COPD), new research suggests.

The average woman in her mid-30s is more than three times as likely to develop the progressive and potentially deadly lung disorder as breast cancer during her lifetime, says respiratory disease specialist Andrea Gershon, MD. She says the average man is more than three times as likely to develop COPD as prostate cancer.

Gershon conducted the first comprehensive assessment of lifetime COPD risk by analyzing data from three separate Canadian health registries.

COPD is one of the most common lung diseases and causes of death in older people.

Many people with COPD actually have a mix of two conditions: chronic bronchitis and emphysema. In chronic bronchitis, the airways to the lungs become inflamed. In emphysema, the air sacs that carry air through the lungs stop functioning.

Smoking is the leading cause of COPD. New research suggests that the risk of developing the disease may be higher for both smokers and nonsmokers than previously recognized.

"This is a disease that is underreported. But it is still the fourth leading cause of death worldwide and it is projected to be the third cause of death within two decades," Gershon tells WebMD.

Calculating COPD Risk

The study included data on close to 13 million adults in their mid-30s or older living in Ontario, Canada. They were followed for up to 14 years.

Because the registries did not include information on smoking history, it was not clear how many of those included in the analysis were current or former smokers and how many had never smoked.

Even though the registries certainly included nonsmokers, the overall lifetime risk for developing COPD by the age of 80 was still 27%, Gershon says.

Among the other major findings:

The lifetime risk was higher for men than women (29% vs. 25%) and for people of lower socioeconomic status compared to higher status (32% vs. 23%).

People living in rural communities had a higher lifetime risk than people living in urban areas (32% vs. 26%).

The lifetime risk for COPD was comparable to that of diabetes and asthma, roughly double that of developing congestive heart failure, and three to four times greater than the risk for having a heart attack.

The study did not address the specific risk to smokers. Previous estimates have suggested that between 15% and 50% of longtime smokers develop COPD.

The latest findings indicate that the real figure is closer to 50% than 15%, University of Michigan Health System professor of internal medicine Fernando J. Martinez, MD, tells WebMD.

In an editorial published with the study, Martinez wrote that the findings highlight the largely unrecognized burden of the disease.

The study and editorial appear in the Sept. 10 issue of The Lancet.

"Until recently, there has been little public awareness about COPD and the disease has received few resources from funding agencies," he writes. "The amount spent on research per case of COPD still lags behind that of other chronic and malignant diseases."

Not Just a Smoker's Disease

Gershon says the perception that only smokers get COPD may explain why it has not received the same funding for research as diseases of comparable burden.

"We know that this is not just a disease of smokers," she says. "It is true that most patients are smokers or former smokers, but people who have never smoked also get it."

Recent research suggests that children with asthma may have an increased risk for COPD later in life.

Martinez says the link between asthma and COPD should be a central focus of future research.

Pulmonary specialist Len Horovitz, MD, of New York City's Lenox Hill Hospital, says more research is also needed to understand nonsmoking-related causes of COPD.

He tells WebMD that about one in 10 of his COPD patients are not longtime smokers or former smokers.

"People need to realize that even if they don't smoke, they could get COPD," he says. "Anyone with a job or hobby that involves inhaling noxious [fumes] might be at risk."